Phase Transformations of Iron-Sulfur Alloys Under Extreme Conditions of Earth and Super-Earths

The inner cores of Earth and super-Earths are primarily composed of iron alloyed with small amounts of light elements. Sulfur, a key alloying element, plays a crucial yet poorly understood role in shaping core structure. Developing accurate interior models of rocky planets requires a precise understanding of the geophysical properties of iron-sulfur alloys under extreme pressure and temperature conditions. To address this, first-principles quantum molecular dynamics (QMD) simulations are employed to investigate phase transitions, including melting, and to determine the Fe-S equation of state. These insights will guide the design, analysis, and interpretation of dynamic compression experiments at the Omega EP high-power facility at the Laboratory for Laser Energetics. Furthermore, the extensive QMD dataset is being leveraged to develop a machine-learning interatomic potential for Fe-S, enabling large-scale molecular dynamics (MD) simulations of dynamic compression of iron-sulfur alloys. Large scale MD will facilitate direct comparison with experiment, advancing our understanding of planetary interiors.